Solid state imaging element and electronic device
The present disclosure relates to a solid state imaging element and an electronic device that make it possible to improve sensitivity to light on a long wavelength side. A solid state imaging element according to a first aspect of the present disclosure has a solid state imaging element in which a large number of pixels are arranged vertically and horizontally, the solid state imaging element includes a periodic concave-convex pattern on a light receiving surface and an opposite surface to the light receiving surface of a light absorbing layer as a light detecting element. The present disclosure can be applied to, for example, a CMOS and the like installed in a sensor that needs a high sensitivity to light belonging to a region on the long wavelength side, such as light in the infrared region.
1. A light detecting device, comprising:
a first light detecting element and a second light detecting element disposed in a silicon layer;
an isolation structure disposed between the first light detecting element and the second light detecting element;
a first concave-convex pattern included in a first surface of the silicon layer, the first surface being a light receiving surface; and
a second concave-convex pattern included in a second surface of the silicon layer that is opposite the first surface,
wherein a period of the first concave-convex pattern and a period of the second concave-convex pattern vary based on a wavelength of light that is to be sensed by the first and second light detecting elements,
wherein a shape of the first concave-convex pattern is different than a shape of the second concave-convex pattern in a cross-sectional view,
wherein the first concave-convex pattern and the second concave-convex pattern are one of one-dimensional or two-dimensional,
wherein the shape of the first concave-convex pattern is inverted triangular in the cross-sectional view, and
wherein the shape of the second concave-convex pattern is quadrangular in the cross-sectional view.
2. The light detecting device according to claim 1 , further comprising:
a reflecting mirror structure disposed below the first light detecting element and the second light detecting element.
3. The light detecting device according to claim 2 , wherein the reflecting mirror structure is planar in the cross-sectional view.
4. The light detecting device according to claim 3 , wherein, in the cross-sectional view, the reflecting mirror structure extends under the isolation structure.
5. The light detecting device according to claim 1 , wherein a first crystal plane of the second surface is (100), and wherein a second crystal plane of a wall surface of the second concave-convex pattern is (111).
6. The light detecting device according to claim 1 , wherein a period of the first concave-convex pattern is 1 μm or less.
7. The light detecting device according to claim 1 , wherein the silicon layer is made of single crystal silicon.
8. The light detecting device according to claim 1 , wherein the isolation structure is made of a material of a first refractive index lower than a second refractive index of the first light detecting element.
9. The light detecting device according to claim 1 , wherein the isolation structure comprises a metal reflecting wall.
10. The light detecting device according to claim 1 , wherein the first concave-convex pattern and the second concave-convex pattern have a substantially same period.
11. The light detecting device according to claim 1 , wherein a width of a part of the first concave-convex pattern is different from a width of a part of the second concave-convex pattern in the cross-sectional view.
12. The light detecting device according to claim 1 , wherein a widest section of the inverted triangular shape of the first concave-convex pattern has a width that is less than or equal to a period of the first concave-convex pattern.
13. The light detecting device according to claim 12 , wherein a depth of the inverted triangular shape of the first concave-convex pattern is less than the width of the widest section.
14. The light detecting device according to claim 1 , wherein a depth of the inverted triangular shape of the first concave-convex pattern is between 0.3*W 1 and 1.0*W 1 , where W 1 is a width of a widest part of an opening that defines the inverted triangular shape in the first concave-convex pattern.
15. An electronic device, comprising:
a light detecting device, wherein the light detecting device comprises:
a first light detecting element and a second light detecting element disposed in a silicon layer;
an isolation structure disposed between the first light detecting element and the second light detecting element;
a first concave-convex pattern included in a first surface of the silicon layer, the first surface being a light receiving surface; and
a second concave-convex pattern included in a second surface of the silicon layer that is opposite the first surface,
wherein a period of the first concave-convex pattern and a period of the second concave-convex pattern vary based on a wavelength of light that is to be sensed by the first and second light detecting elements,
wherein a shape of the first concave-convex pattern is different than a shape of the second concave-convex pattern in a cross-sectional view,
wherein the first concave-convex pattern and the second concave-convex pattern are one of one-dimensional or two-dimensional,
wherein the shape of the first concave-convex pattern is inverted triangular in the cross-sectional view, and
wherein the shape of the second concave-convex pattern is quadrangular in the cross-sectional view.
16. The electronic device according to claim 15 , further comprising:
a reflecting mirror structure disposed below the first light detecting element.
17. The electronic device according to claim 16 , wherein the reflecting mirror structure is planar in the cross-sectional view.